1. Field of the invention
The present invention relates to a display device and a manufacturing method of a display device, and more particularly to a technique which is effectively applicable to a liquid crystal display panel which is manufactured using a liquid crystal material dropping method.
2. Description of the Related Art
As a display device of a television receiver set or a personal computer, a liquid crystal display panel has been used conventionally.
The liquid crystal display panel is formed by filling and sealing a liquid crystal material between two substrates on which transparent electrodes are formed. The liquid crystal display panel displays an image by controlling the transmission and the interruption of light by applying a voltage to the liquid crystal material.
Conventionally, as a method for filling and sealing the liquid crystal material in the liquid crystal display panel, in general, a vacuum sealing (filling) method has been used. In the vacuum sealing method, first of all, two substrates are adhered to each other using a sealing material. Here, the sealing material is formed in an annular shape while partially forming a gap therein. This gap is referred to as a filling port. The liquid crystal is filled into the inside of the sealing material from the filling port.
First of all, the filling port is immersed into the liquid crystal material in a vacuum atmosphere. Next, along with the increase of a pressure of an outer space, the liquid crystal is filled into a space surrounded by the substrates and the sealing material. Thereafter, the filling port is sealed with the sealing material thus completing the liquid crystal display panel.
However, the liquid crystal display panel which is used in a display device such as a television receiver set, recently, the large-sizing has been in progress and the filling of the liquid crystal material using the vacuum sealing method is becoming more and more difficult.
In view of such circumstances, as a sealing method of a liquid crystal material, a liquid crystal material dropping method has been proposed in U.S. Pat. No. 6,956,636 in place of the vacuum sealing method.
The above-mentioned liquid crystal material dropping method is a method which, for example, seals a liquid crystal material simultaneously when two substrates are adhered to each other. After forming the sealing material on one substrate in an annular shape, a liquid crystal material is dropped in the inside of a region which is surrounded by the sealing material. Thereafter, another substrate is overlapped to one substrate and two substrates are adhered to each other by hardening the sealing material thus completing a liquid crystal display panel.
In the above-mentioned liquid crystal material dropping method, a dropping quantity of the above-mentioned liquid crystal material is determined based on, for example, a height of spacers which determines a gap between two substrates and an area of a region surrounded by the sealing material.
However, in the liquid crystal material dropping method, for example, due to the irregularities of the dropping quantity of the liquid crystal material when the liquid crystal material is dropped, the dropping quantity of the liquid crystal material with respect to the space in which the liquid crystal material is sealed may be changed.
When the dropping quantity of the liquid crystal material is changed, there arise irregularities among individual products and hence, there arises a drawback that the characteristic of the display device differs among respective individual products.